linux-kernel - [tip: x86/cpu] tools/x86/kcpuid: Save CPUID output in an array

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Message-ID: <174289354545.14745.3592894898931165685.tip-bot2@tip-bot2>
Date: Tue, 25 Mar 2025 09:05:45 -0000
From: "tip-bot2 for Ahmed S. Darwish" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Ahmed S. Darwish" <darwi@...utronix.de>, Ingo Molnar <mingo@...nel.org>,
 "H. Peter Anvin" <hpa@...or.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: x86/cpu] tools/x86/kcpuid: Save CPUID output in an array

The following commit has been merged into the x86/cpu branch of tip:

Commit-ID:     6bef74cab03ada39f16f1fb86b732f7c71a9f07a
Gitweb:        https://git.kernel.org/tip/6bef74cab03ada39f16f1fb86b732f7c71a9f07a
Author:        Ahmed S. Darwish <darwi@...utronix.de>
AuthorDate:    Mon, 24 Mar 2025 15:20:25 +01:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Tue, 25 Mar 2025 09:53:44 +01:00

tools/x86/kcpuid: Save CPUID output in an array

For each CPUID leaf/subleaf query, save the output in an output[] array
instead of spelling it out using EAX to EDX variables.

This allows the CPUID output to be accessed programmatically instead of
calling decode_bits() four times.  Loop-based access also allows "kcpuid
--detail" to print the correct output register names in next commit.

Signed-off-by: Ahmed S. Darwish <darwi@...utronix.de>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Link: https://lore.kernel.org/r/20250324142042.29010-5-darwi@linutronix.de
---
 tools/arch/x86/kcpuid/kcpuid.c | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/tools/arch/x86/kcpuid/kcpuid.c b/tools/arch/x86/kcpuid/kcpuid.c
index a90ac0b..8da0e07 100644
--- a/tools/arch/x86/kcpuid/kcpuid.c
+++ b/tools/arch/x86/kcpuid/kcpuid.c
@@ -51,7 +51,7 @@ static const char * const reg_names[] = {
 struct subleaf {
 	u32 index;
 	u32 sub;
-	u32 eax, ebx, ecx, edx;
+	u32 output[NR_REGS];
 	struct reg_desc info[NR_REGS];
 };
 
@@ -119,11 +119,11 @@ static void leaf_print_raw(struct subleaf *leaf)
 		if (leaf->sub == 0)
 			printf("0x%08x: subleafs:\n", leaf->index);
 
-		printf(" %2d: EAX=0x%08x, EBX=0x%08x, ECX=0x%08x, EDX=0x%08x\n",
-			leaf->sub, leaf->eax, leaf->ebx, leaf->ecx, leaf->edx);
+		printf(" %2d: EAX=0x%08x, EBX=0x%08x, ECX=0x%08x, EDX=0x%08x\n", leaf->sub,
+		       leaf->output[0], leaf->output[1], leaf->output[2], leaf->output[3]);
 	} else {
-		printf("0x%08x: EAX=0x%08x, EBX=0x%08x, ECX=0x%08x, EDX=0x%08x\n",
-			leaf->index, leaf->eax, leaf->ebx, leaf->ecx, leaf->edx);
+		printf("0x%08x: EAX=0x%08x, EBX=0x%08x, ECX=0x%08x, EDX=0x%08x\n", leaf->index,
+		       leaf->output[0], leaf->output[1], leaf->output[2], leaf->output[3]);
 	}
 }
 
@@ -163,10 +163,10 @@ static bool cpuid_store(struct cpuid_range *range, u32 f, int subleaf,
 
 	leaf->index = f;
 	leaf->sub = subleaf;
-	leaf->eax = a;
-	leaf->ebx = b;
-	leaf->ecx = c;
-	leaf->edx = d;
+	leaf->output[R_EAX] = a;
+	leaf->output[R_EBX] = b;
+	leaf->output[R_ECX] = c;
+	leaf->output[R_EDX] = d;
 
 	return false;
 }
@@ -490,10 +490,8 @@ static void show_leaf(struct subleaf *leaf)
 				leaf->index, leaf->sub);
 	}
 
-	decode_bits(leaf->eax, &leaf->info[R_EAX], R_EAX);
-	decode_bits(leaf->ebx, &leaf->info[R_EBX], R_EBX);
-	decode_bits(leaf->ecx, &leaf->info[R_ECX], R_ECX);
-	decode_bits(leaf->edx, &leaf->info[R_EDX], R_EDX);
+	for (int i = R_EAX; i < NR_REGS; i++)
+		decode_bits(leaf->output[i], &leaf->info[i], i);
 
 	if (!show_raw && show_details)
 		printf("\n");